• Title/Summary/Keyword: Fire Mechanism

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Progressive Collapse of Steel High-Rise Buildings Exposed to Fire: Current State of Research

  • Jiang, Jian;Li, Guo-Qiang
    • International Journal of High-Rise Buildings
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    • v.7 no.4
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    • pp.375-387
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    • 2018
  • This paper presents a review on progressive collapse mechanism of steel framed buildings exposed to fire. The influence of load ratios, strength of structural members (beam, column, slab, connection), fire scenarios, bracing systems, fire protections on the collapse mode and collapse time of structures is comprehensively reviewed. It is found that the key influencing factors include load ratio, fire scenario, bracing layout and fire protection. The application of strong beams, high load ratios, multi-compartment fires will lead to global downward collapse which is undesirable. The catenary action in beams and tensile membrane action in slabs contribute to the enhancement of structural collapse resistance, leading to a ductile collapse mechanism. It is recommended to increase the reinforcement ratio in the sagging and hogging region of slabs to not only enhance the tensile membrane action in the slab, but to prevent the failure of beam-to-column connections. It is also found that a frame may collapse in the cooling phase of compartment fires or under travelling fires. This is because that the steel members may experience maximum temperatures and maximum displacements under these two fire scenarios. An edge bay fire is more prone to induce the collapse of structures than a central bay fire. The progressive collapse of buildings can be effectively prevented by using bracing systems and fire protections. A combination of horizontal and vertical bracing systems as well as increasing the strength and stiffness of bracing members is recommended to enhance the collapse resistance. A protected frame dose not collapse immediately after the local failure but experiences a relatively long withstanding period of at least 60 mins. It is suggested to use three-dimensional models for accurate predictions of whether, when and how a structure collapses under various fire scenarios.

A Study of the Ignition Mechanism in Electric Condenser Iksan Firestation (콘덴서의 발화 메커니즘 실험)

  • Kim, Sang-Soon;Lee, Jae-Wook
    • Journal of the Korea Safety Management & Science
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    • v.23 no.3
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    • pp.103-113
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    • 2021
  • As the use of capacitors in electrical appliances and electrical control circuits increases, the related electrical fire is increasing. There are various parts such as resistors, coils, and capacitors that make up an electric circuit. Among them, the ignition of a capacitor with a temporary charging function is closely related to the structural characteristics of the capacitor. Capacitors can explode due to various reasons, and the high heat generated when they explode ignites the inflammable dielectric, which in turn burns the inflammable materials such as the surrounding electric wires and spreads into a fire. In this paper, the ignition mechanism is studied by conducting a reenactment experiment on the various probabilities that can be ignited in an electric capacitor, and the prevention measures to be applied to the fire prevention are presented.

Numerical Study on the Effects of Spray Properties of Water Mist on the Fire Suppression Mechanism (미분무수 특성이 화재억제 메커니즘에 미치는 영향에 대한 수치해석적 연구)

  • Bae, Kang-Youl;Chung, Hee-Taeg;Kim, Hyoung-Bum
    • Journal of ILASS-Korea
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    • v.22 no.4
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    • pp.175-184
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    • 2017
  • The numerical investigation on the effects of water-mist characteristics has been carried out for the fire suppression mechanism. The FDS are used to simulate the interaction of fire plume and water mists, and program describes the fire-driven flows using LES turbulence model, the mixture fraction combustion model, the finite volume method of radiation transport for a non-scattering gray gas, and conjugate heat transfer between wall and gas flow. The numerical model is consisted of a rectangular enclosure of $L{\times}W{\times}H=1.5{\times}1.5{\times}2.0m^3$ and a water mist nozzle that be installed 1.8 m from fire pool. In the present study, the parameters of nozzle for simulation are the droplet size and the spray velocity. The droplet size influences to fire flume on fire suppression more than the spray velocity because of the effect of the terminal velocity. The optimal condition for fire suppression is that the droplet size and the spray velocity are $100{\mu}m$ and 20 m/s respectively.

Design of an Automatic Target Sensing and Triggering System (적외선 감지 자동격발장치의 설계)

  • Hong S.H.;Kim K.H.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.06a
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    • pp.1719-1723
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    • 2005
  • An automatic target sensing and triggering system for small fire arms is proposed. The system consists of an optical collector, an infrared ray sensor responsive to human body temperature, an electric actuator and a trigger mechanism. TRIZ methodologies are used to develop solutions to several contradictory problems. Experimental results on the system performance is compared with predictions.

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The Testing Methods of the Fire and the Electric Shock on the Electric Pad Using the House (가정용 전기매트에 대한 화재 및 감전 시험법에 관한 연구)

  • Jang, In-Hyeok;Lee, Chang-Hoon;Lee, Young-Joo;Lim, Houng-Woo
    • Journal of Applied Reliability
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    • v.14 no.3
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    • pp.169-175
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    • 2014
  • In this paper, the evaluating test methods of the fire and the electric shock on the Electric pad using the house is proposed. We analyzed electric pad using magnetic shielded type hot wire because electric pad using the magnetic shielded type hot wire generally be used in the home. We analyzed FMEA in order to analyze the mechanism of the fire and the electric shock of the electric pad and designed testing methods (Durability tests on the environment, Mechanical durability tests, Electrical durability tests) obtained through the two-step QFD and tested. We verified the evaluating test methods of the fire and the electric shock on the Electric pad using the house through the analysis of the test results.